Help Please.................?

My horses has some places on the side of his head and on his leg, and i bought some stuff and its been like a month and it only healed one of his places. I was thinking about buying ( Corona Ointment ) i' ve seen it in books and i hear its good, but im not sure. Does anyone use it and if so does it work good and how long does it take for it to heal the places? Or does some one know something that works good that's not really pricey. Thanks a lot!